📚 C++ Library Management System

A console-based Library Management System built with modern C++ design practices. It uses OOP, SOLID principles, and core design patterns to manage library operations such as issuing and returning books, managing members, and maintaining library ownership control.

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🚀 Tech Stack

• Language: C++17
• Build Tool: g++ / clang++
• Execution Environment: Command-Line Interface (CLI)
• Architecture: Object-Oriented + Design Patterns

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🎯 Core Features

• 📖 Manage different types of books (EBook and HardCopy)
• 👥 Handle Members and the Owner of the library
• 📌 Issue and return books
• 🧾 Track issued books per member
• 🚫 Owner can remove members (only if they’ve returned all books)
• 🧩 Extensible structure using abstract base classes

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🧠 Object-Oriented Principles Used

• Encapsulation: All data members are private/protected and exposed via public methods.
• Inheritance: Book → EBook, HardCopy; User → Member, Owner
• Polymorphism: Virtual methods allow dynamic behavior (e.g., book type handling).
• Abstraction: Abstract base classes (Book, User) hide unnecessary implementation details.

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📐 SOLID Principles Applied

Principle	Description
S - Single Responsibility	Each class has a single responsibility (e.g., Book, Library, Member)
O - Open/Closed	Code is open for extension, closed for modification via inheritance and polymorphism
L - Liskov Substitution	Derived classes (EBook, HardCopy) can replace their base class Book without issues
I - Interface Segregation	Abstract base classes ensure each user/book type only uses relevant functionality
D - Dependency Inversion	Strategy pattern decouples issue/return behavior from core classes

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🏗️ Design Patterns Used

Pattern	Description
Singleton	The Library class is a singleton — only one instance manages the entire library
Strategy	Different strategies for issuing/returning books (can be extended if needed)
Factory (Partial)	Object creation logic for books (EBook, HardCopy) and users is abstracted in logic blocks (can be fully extended later)

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📌 UML Diagram (Class Structure)

              +--------------------+
              |      Book          |  <<abstract>>
              +--------------------+
              | -id                |
              | -title             |
              | -author            |
              +--------------------+
              | +displayDetails()  |
              +--------------------+
                 /         \
                /           \
+------------------+   +-------------------+
|     EBook        |   |   HardCopy        |
+------------------+   +-------------------+
| -downloadLink    |   | -shelfNumber      |
+------------------+   +-------------------+
| +displayDetails()|   | +displayDetails() |
+------------------+   +-------------------+

              +---------------------+
              |       User          | <<abstract>>
              +---------------------+
              | -id                 |
              | -name               |
              +---------------------+
              | +displayInfo()      |
              +---------------------+
                  /         \
                 /           \
+-------------------+   +--------------------+
|      Member       |   |       Owner        |
+-------------------+   +--------------------+
| -borrowedBooks[]  |   |                    |
+-------------------+   +--------------------+
| +borrowBook()     |   | +add/remove member |
| +returnBook()     |   | +view stats        |
+-------------------+   +--------------------+

                +-------------------+
                |     Library       | <<Singleton>>
                +-------------------+
                | -books[]          |
                | -members[]        |
                | -owner            |
                +-------------------+
                | +getInstance()    |
                | +addBook()        |
                | +issueBook()      |
                | +removeMember()   |
                +-------------------+

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📈 Future Improvements

• 🧑‍💻 Admin/Staff Roles: Introduce additional roles like Librarian or Staff, with permission levels between Owner and Member, for tasks like issuing books or managing daily operations.
• 🗃️ Persistent Storage: Replace in-memory storage with file I/O or a database (like SQLite or MySQL) to persist library data between sessions.
• 🌐 GUI Support: Build a lightweight GUI using libraries like Qt or ImGui to make it more user-friendly than the CLI.
• 🔒 Role-Based Access Control (RBAC): Strengthen access checks through an RBAC system to restrict features by user role more securely.

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Author

• Anmol kumar
• linkedin - https://www.linkedin.com/in/anmol-kumar-1ba37b324/